medwireNews: A French study has shown that the seroconversion rate after two doses of the Pfizer–BioNTech (BNT162b2) COVID-19 vaccine is high among people with cancer, but antibody titers remain low, especially among those who are receiving chemotherapy.
“[A]nti-spike antibody titers were 3-10 times lower in patients with [solid cancers] than in healthy controls, raising concerns about impaired humoral immunity,” say Romain Palich (Pitié-Salpêtrière Hospital, Paris) and colleagues in a letter to the Annals of Oncology.
They add: “At the same time, the seroconversion data are rather reassuring among patients on anti-HER2, anti PD-1/PD-L1, antiangiogenic treatment or hormone therapy without associated chemotherapy.”
The team notes, however, that “further studies are required to determine the […] correlates of vaccine-induced protection based on neutralizing antibodies and cellular immunity” as well as to determine when a third vaccine dose should be offered to cancer patients.
The study included 223 patients with cancer and 49 cancer-free controls who received two doses of the Pfizer–BioNTech vaccine between January 5 and April 2, 2021. The cancer patients were aged a median of 67 years and 58% were receiving chemotherapy at the time of vaccination.
The seroconversion rate 3–4 weeks after the second dose was 94% among patients with cancer and 100% among healthy controls, but the median anti-spike antibody titer was significantly lower in the former group, at 252 versus 2517 UA/mL with the Elecsys assay (Roche Diagnostics Ltd, Burgess Hill, UK), and 4443 versus 13,285 U/mL with the Alinity assay (Abbott Laboratories, Abbott Park, Illinois, USA).
The median titer was also significantly lower in cancer patients who were receiving chemotherapy (either alone or in combination with other treatments) versus those who were not, at 227 versus 896 UA/mL with the Elecsys assay, and 1901 versus 6094 U/mL with the Alinity assay.
There was no significant difference in antibody titers between cancer patients aged at least 65 years and those who were younger and between those with and without metastases, regardless of the assay used.
“[T]he mRNA vaccine boost led to a high seroconversion rate, reinforcing the need not to delay the second dose” in people with cancer, write the researchers.
And they conclude: “Pending additional data, we would highly recommend vaccination for family and friendship circles, to provide an indirect protection against COVID-19 to this population.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group
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Ann Oncol 2021; doi:10.1016/j.annonc.2021.06.018